This example shows operation of a Kinetic Energy Recovery System (KERS) on a Formula 1 car. The model permits the benefits to be explored. During braking, energy is stored in a lithium-ion battery and ultracapacitor combination. It is assumed that a maximum of 400KJ of energy is to be delivered in one lap at a maximum power of 60KW. Design parameters are the weight of the battery, ultracapacitor and motor-generator. If these parameters are all set to the very small value of 0.01kg, the lap time is 95.0 seconds, this corresponding to a car with no KERS. With default values set here, approximately 1/3 of a second is saved on the lap time when using Strategy 1 which uses any available electrical power when not braking. Strategy 2 applies KERS only to selected corners, and requires a larger ultracapacitor to show any significant benefit.
This model shows how SimElectronics® and Simscape™ can be used to support system-level design. The KERS performance is a complex trade-off between the masses of the three main components (battery, ultracapacitor and motor-generator), plus the energy-management strategy. The KERS system adds mass which reduces acceleration due to the engine. The stored electrical energy from braking must more than compensate for this. Lithium-ion batteries have a very high energy per unit mass but a poor power per unit mass. Conversely an ultracapacitor has relatively low energy per unit mass, but a very high power per unit mass which suits this particular application.